RESUMEN
The authors present a case of radiation-induced pacemaker failure. After 2,000 rad (20 Gy) of photon irradiation for metastatic bronchogenic carcinoma, the pulse generator circuitry failed, producing a "runaway" rhythm. This suggests that present pacemaker circuitry may be more susceptible to irradiation than previously believed, and that even modest radiation doses can induce life-threatening arrhythmias.
Asunto(s)
Arritmias Cardíacas/etiología , Marcapaso Artificial/efectos adversos , Radiación Ionizante , Carcinoma Broncogénico/radioterapia , Electrocardiografía , Electrónica , Femenino , Humanos , Neoplasias Pulmonares/radioterapia , Persona de Mediana EdadAsunto(s)
Arritmias Cardíacas/prevención & control , Infarto del Miocardio/complicaciones , Animales , Antiarrítmicos/uso terapéutico , Arritmias Cardíacas/tratamiento farmacológico , Arritmias Cardíacas/fisiopatología , Electrofisiología , Sistema de Conducción Cardíaco/fisiopatología , Ventrículos Cardíacos , Humanos , Lidocaína/uso terapéutico , Procainamida/uso terapéuticoRESUMEN
Although many different beta blockers are now in clinical use, there is very little information concerning their relative efficacy, and it is still not clear what clinical importance should be attached to properties such as positive inotropic stimulation (intrinsic sympathomimetic activity or ISA) and membrane stabilizing action ("local anaesthetic effect" or "quinidine-like effect"). In this report we compare the ability of patients with angina to exercise on a bicycle ergometer while receiving a series of commonly used beta blockers, and attempt to determine the importance of ISA. The investigation is in four parts with the drugs given orally or intravenously: statistical analysis of the results was carried out using standard methods, both parametric and non-parametric (Friedmann analysis of variance, Wilcoxon matched pairs signed ranks test) by two independent statisticians. The relevant properties of drugs included in this paper are summarized in Table I. Laboratory reports using many different animal preparations may differ from this assessment under specific conditions, and the Table is intended only as a guide to the generally accepted properties of these drugs when used clinically. Results for sotalol are included for reference in the first part of this paper but the drug was withdrawn from clinical use and was not studied further.